The general research goal is the elucidation of the structure, mechanism of action and role in the cell of phosphate transferring enzymes. Effort is presently concentrated on adenylate kinase from pig and carp. The role of active site groups are being studied by chemical and physical means. While tyrosine is not in the active site cleft of the model as derived from X-ray studies introduction of nitro- or iodo-groups results in decreased activity.